Telephone system.



F. IVI. SLOUGH. TELEPHONE SYSTEM. APPucATloN FILED Aue. Il. 1914.

Patented Apr. 10, 1917.'

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FRANK IVI. SLOUGI-I, OF ELYRIA, OHIO, ASSIGNOR, :BY MESNE ASSIGNMENTS,TO STROM- BERG-CARLSON TELEPHONE MFG. CO., OF ROCHESTER, NEI/V YORK, ACORPORATION or New YORK,

TELEPHONE SYSTEM.

LZQZAMS.

Application filed August 17, 1914.

To all whom t may concern.'

Be it known that l, FRANK M. SLoUGH, a citizen of the United States,residing at Elyria, Lorain county, Ohio, have invented certain new anduseful Improvements in Telephone Systems; and I do hereby declare theiollowing to be a full, clear, and eXact description of the same, suchas will enable others skilled in the art to which it appertains to makeand use the same.

My invention relates to telephone systems, and more especially tosystems `in which secret service is provided; that is, means areprovided whereby the operator is excluded during the period when thesubscribers are conversing, though permitted to communicate with thecalling subscriber for the purpose of learning the connection desired. Iaim to accomplish this vresult with as little complication and with theaddition to the system of as little apparatus as possible.

Other objects oii'my invention and the invention itself will probably bebetter understood from a description of specic embodiments of theinvention.

.Figure l is a diagrammatic representation of a telephone systemembodying my invention.

Fig. 2 is a second diagrammatic illustration of a telephone systemembodying my invention.

Fig. 3 is a theoretical diagram for the purpose of illustrating theprinciple of my invention.

Referring iirst to the embodiment trated in Fig. 1, at I and II areillustrated telephone lines, line I being here called the calling lineand line II the called line. Substation apparatus is connected to eachof the lines. At the station A upon line I this apparatus is illustratedas consisting of a transmitter B, a receiver C, a switch hook D and asignal bell E. The station at F upon line II is illustrated merely as asymbol, the

apparatus thereat being substantially the same as that shown at stationA. Of course, either of these lines may be a multi-party line. The mainstation is represented as at III.

'Ihe line I extends by limbs l and 2 to the main station III and theline II, by limbs 3 and l to the main station. Means are provided at themain station for connecting the lines together, which consists ofsuitable link conductors 5 and 6, in the embodiments illusmus'.V

Specification of Letters Patent. Fantasmi-,Qd Api'. l0, 19917.,

Serial No. 857,038.

trated shown in the form of a cord circuit G.. Switching mechanism isprovided for connecting the cord circuit to the telephone lines-ananswering switching mechanism II and a calling switching mechanism K. Inthe form shown, the switching mechanism H is shownl as consisting of aplug P connected to the strands of the cord circuit and a jack Jconnected to the telephone line I. rIhe calling switching mechanism isshown as consisting of a plug P1 connected to the cord G and a jack Ilconnected to the line II. An operators set is provided at the mainstation illustrated at L and including a transmitter B, a receiver C andan induction coil M and other apparatus constituting the essentials oisuch a set. rIbe substation set, the switching means and the operatorsset are all apparatus well known in the art, andthe sub-combinationsconstituting the same are no part of my invention.

Line I is provided with a line signal N, a line relay Q and a cut-oil?relay U. The line II is provided with similar apparatus, the cut-offrelay being shown at V. rIhe cord circuit is provided with supervisorylamps R, R1 and supervisory relays S and S1. The cord circuit isprovidedalso witha supervisory signaling and controlling relay Y,sometimes known as the supervisory relay. This relay is provided withtwo coils 1l and l2. A. relay Z is also provided, which controls theconnection of the operators set to the cord circuit.

The apparatus itself and the purposes will be clear from the followingdescription of the operation of the system.

Assuming the subscriber at A desires to communicate with the subscriberat Fa the receiver C is remo-ved from the hook D in the well knownmanner, and the hook D being spring pressed upward, rises and engagesthe contact 13, completing a circuit through the relay Q, as follows:l-transmitter B-receiver C-conductor l-switch ll-l-relay Q-batteryZMS-switch 17* l8-eonductor Q-.hook switch D. 'Ihe relay Q will beenergized, attracting its armature 2O and closing a switch 20-21 in thecircuit of the lamp N, which includes the battery 16 and the conductorQ2. The lamp N will receive current and be lighted. This lamp being in aposition-where its illumination attracts the attention of the operator,

the operator will insert the plug lj into the jack J, the tip contact23, the ring contact 24 and the sleeve contact 25 engaging respectivelywith the tip spring 26, sleeve spring 27 and thimble 28 of the jack.'Ihe engagement of the Contact 25 with the contact 2S completes acircuit through the relays U, Z and Y, as follows: ground at29-conductor VSO-relay U-conductor 31- contact 28-contact 25-conductor32, the relay Z and the windings 11 and 12 of the relay Y in multiple,battery 1G to groundat The relay U will be energized, attracting itsarmatures 15 and 17 and severing the linesignaland lamp from the line.The relay Y will be energized, attracting its armature 34 and closing aswitch 34-35 in the circuit of the lamp. R. rIlhe lamp R would also beenergized, except that when the plug is inserted, the relay S will alsobe energized, over a circuit as follows: winding 36 of S--both sides ofline and the substation set-6kwinding 3T of S`conductor 3S-battery161`conductor 39. The relay S will attract its armature 40 and open theswitch 40-/l1, so that the lamp R will not be energized. The completingoit the circuit through the relays U, Z and Y also causes theenergization of the relay Z, as stated. This relay will attract itsarmatures 42 and 43,- closing the switches 42-1e, 43-45 and connectingthe operators set to the talking strands 5 and 6 of the cord circuit.The opera-tor will then communicate with the subscriber at A over thefollowingcircuit: C'--4i8-43-45-621l:-27-1-C- B 13-D*226-23-5 50*44t2-51-back to C'. I-Iaving learned that itl is the subscriber at F thatis desired, and assuming that line II is idle, the plug I),L is insertedinto the jack J1, the tip', ring and sleeve contacts of the plugengaging with the tip spring, sleeve spring and thimble o1 the jack J1.A circuit will be' completed as follows: 33-bat tery 161, coil 11 ofrelay Y in multiple with coil 12 of relay Y and relay Zconductor(iO-conductor 56-contact 57-58-Vto ground 59. The relay V will beenergized, cutting ofi1 the line signal lamp of the line II in themanner described in connection with line I, and the relay Z will bedenergized, owing to the fact that the completion of the circuit throughthe relay V' placed the points G1 and 62 at the same potential.

rIhe operation of this portion of apparatus will probablyv be betterunderstood from a reference to Fig. 3where I have illustrated theapparatus in the form oi' a Wheatstone bridge withthe relay Z in thebridge. If the branch including-the coil of the relay Y is open, currentwill flew in two paths, as follows: winding 12 and .winding of relay Uback to 16'; (second path), 16'-80-winding 11 of relay Y-Sl-Z-winding ofU-bacl to (first path), 16', conductor S0-- 1G', the relay Z receivingcurrent. It, hewever, the limb 82, including the winding of relay V isclosed, the bridge will be balanced and current will flow in two pathsas follows: 16'-80-1183-82-V back to the point Se. The second path willbe 16,- -12-86-87Uback to the point 84. The resistances of the devicesU, V, l1 and l2 are so proportioned that the potentials at the points 88and 89 are the same, so that no current will. How through the bridge 81.Consequently, the relay Z will be denergized, releasing its armatures4-2 and 43 and automatically disconnecting the operators set from thecord circuit. After the called subscriber is signaled by the ringing ofhis bell, and after he replies, the conversation talres place over theconductors 1, 2, 5, G, 3. and 4, the operator being disconnected duringthis period. When the conversation is terminated, -the restoration ofthe receivers to the hoo-ks causes the denergization of the relays S andS1, whereupon the circuits of the lamps R and R, are closed, indicatingto the operator that the conversao@ tion is completed, whereupon shewithdraws the plugs from the jacks and the system is restored to normal.

In the modification shown in Fig. 2, insteadof using inductiveresistances, or windings of a relay, as for example at Y in Fig. l Ihave employed special non-inductive resistances 11 and 12'. Theoperation of this system would be the same as that described inconnection with the modification shown 10e in Fig. 1. The operators setis illustrated at O', the relay controlling the same at Z', the callingline at I', the cut-off relay at U', line lamp at N', line relay at Q',lnultiple jacks of the calling line at J' and J", an- 105 swering plug'at P', calling plug at P" and the supervisory relays at S' and S".

It will, of: course, be understood that auv suitable resistance devicesmay be employed, though it will be seen that in the modiiication shownin Fig. 1 I have utilized the resistance or" the sleeve supervisoryrelays for the purpose of accomplishing the desired functions, and havein fact provided a cord circuit with secret listening service with onlyfour relays, the number ordinarily employed in an ordinary cord circuitwhich does not furnish secret listening service.

I have illustrated these forms and these details for the purpose ofclearly illustrating the invention, and not that I desire to be limitedto the same. I contemplate many modifications and departures from theseforms and details without departing from the spirit of the invention.

I claim:

1. In a telephone system, the combination of a main station, a pluralityoi substations, telephone lines connecting the main station and thesubst-ations, link conductors at the 130 main station for connecting thetelephone lines together, supervisory apparatus associated with saidlink conductors, an operators set at the main station, means forcontrolling the connection of the operators set to the link conductorsincluding a relay provided with a winding, means including a portion ofsaid supervisory apparatus to create at the terminals of said relaywinding different electrical potentials when the link conductors areconnected to one line, and means to create at the terminals of saidrelay winding the same electrical potential when the link conductors areconnected to a plurality of telephone lines.

2. 1n a telephone system, the combination of a main station, a pluralityof substations, telephone lines connecting the substations to the mainstation, a cord circuit at the main station adapted to be connected toone or more lines, supervisory apparatus associated with said cord, anoperators set at the main station, means for connecting the operatorsset to the talking strands of the cord circuit, a relay controlling theconnection of the operators set to the cord circuit, means forenergizing said relay when the cord circuit is connected to onetelephone line and means including a portion of said supervisoryapparatus for shunting the flow of electrical current from said relaywhen the cord circuit is connected to a plurality of telephone lines.

3. In a telephone system, the combination of a main station, a pluralityof substations, telephone lines connectingthe substations to the mainstation, a cord circuit at the main station adapted to be connected ateach end to a telephone line, supervisory apparatus associated with saidcord circuit, an operators set at the main station, means to connect theoperators set to the cord circuit, a relay controlling` the connectionof the operators set to the cord circuit, means for completing a circuitthrough said relay and a portion of said supervisory apparatus when oneend of the cord circuit is connected to a telephone line and means forcreating a shunt about said relay when each end of the cord circuit isconnected to a telephone line.

4. ln a telephone system, the combination of a telephone line and a cordcircuit, switching means for connecting the telephone lines to the cordcircuit, supervisory apparatus including a pair of supervisory relaywindings, an operators set, means to connect the operators set to thecord circuit, a relayr controlling said means, a pair of circuits havinga source of current in common, each of said circuits including one ofsaid supervisory relay windings leading through one of the switchingmeans for connecting the cord to a telephone line and a bridge of saidcircuits including said relay.

5. ln a. telephone system, the combination of telephone lines and a cordcircuit, switching means for connecting each end of the cord to atelephone line, a pair of supervisory relay windings associated withsaid cord circuit, an operators set, means to connect the operators setto a telephone line, a. relay controlling said means, a pair ofcircuits, each of which includes a supervisory relay winding andcontacts of one oi' said switching means, and a bridge ot said circuitsincluding said relay.

G. In a telephone system, the combination of telephone lines, linkconductors for connecting said lines together', switching means forconnecting the link conductors to two telephone lines, an operators setand means to connect the operators set to the link conductors,supervisory means including resistance devices, a pair of electriccircuits each of which includes one of said resistance devices andcontacts of the switching meas for connecting the link conductors totelephone lines, a bridge of said circuits and a relay in said bridgecontrolling the means for connecting the operators set to the linkconductors.

7. n a telephone system, the combination of telephone lines, and linkconductors for connecting said telephone lines together, cutoii"mechanism for each oi' said lines including a resistance device, anoperators set and means for connecting the operators set to the linkconductors, a pair of circuits, each of which includes one of saidresistance devices of the line cut-oli' mechanism and contacts of oneoi' said switching means, a bridge of said conductor and a relay in saidbridge controlling the means for connecting the operators set to thelink conductors.

8. In a telephone system, the combination of telephone lines and linkconductors for connecting the telephone lines together, switching meansfor connecting the link conductors to telephone lines, an operators set,means for connecting the operators set to said link conductors, cut-ofimechanism for each telephone line including a resistance device,additional resistance devices in said system, a pair of circuits each ofwhich includes one of said cut-oiiz' resistance devices and one of saidother resistance devices and contacts of one of said switching means, abridge of said circuits connected to each bridge between the resistancedevices therein, and a relay in said bridge controlling the n'ieans ttorconnecting the operators set to the link conductors.

9; In a telephone system, the combination of telephone lines and linkconductors for connecting the telephone lines together,

switching means for connecting the link con-" ductors to each telephoneline, an operators set and means for connecting the operators set to thelink conductors, supervisory mechanism associated with the linkconductors including resistance devices, cut-ott mechanism associatedwith each telephone line, in-

cluding a cut-Off resistance device, two circuits each of which includesa cut-oill resistance device, a supervisory resistance device andcontacts of one of said switching means and a bridge of said circuitsbetween the resistance devices included therein, and a relay in saidbridge controlling the means for connecting the operators set to thelink conductors. i

10. In a telephone system, the combination of telephone lines and linkconductors for connecting thesame together; a line circuit associatedwith each telephone line, switching means for connectingthe linkconductors to telephone lines, a resistance in each line circuit, anoperators set and means to connect the operators set to the linkconductors, a pair of circuits each of which includes one of saidresistances in a line circuit and contacts of one of said switchingmeans and a relay in bridge of said conductors controlling the means forconnecting the operators set to the link conductors.

11. In a telephone system, the combination of telephone lines and linkconductors for connecting the telephone lines together, switching meansfor connecting the link conductors to the telephone lines, an operatorsset and means for connecting the operators set to the link conductors, acut-oil relay in each line circuit, a pair of supervisory windings and apair of circuits each of which includes one of said supervisorywindings, the

winding of a cut-off relay and contacts of one oi' said switching means,a bridge oi said circuits connected thereto between the supervisorywinding and the cut-oil'l rela and a relay in said bridge controllingthe means for connecting the opcratmfs set to the link conductors.

12. In a telephone system, the combination of telephone lines and a cordcircuit, supervisory apparatus associated with said cord circuit, anoperators set and means controlling` the connection of the operators setto the cord circuit including a relay, a Wheatstone bridge circuitincluding supervisory apparatus, portions of the cord and line circuits,and a relay in the neutral conductor of said bridge controlling theconnection of the operators set to the cord circuit.

13. In a telephone system, the combination of telephone lincs, means toconnect the telephone lines together, supervisory apparatus associatedwith said cord circuit, an operators set, means controlling theconnection of the operators set to said first named means including arelay, a VVheatstcne bridge circuit associated with said lines and saidirst named means, said bridge including supervisory apparatus and aneutral conductor in which the winding of said relay is connected.

In witness whereof, I have signed my namein the presence of twowitnesses this 8th day of August, 1914.

FRANK M. SLOUGH.

Witnesses:

GEO. E. ROBERTS, JOHN PnHnssoN.

Copies of this patent may be obtained for-ive cents each, by addressingthe Commissioner of Patents, Washington, D. C.

